Messages in this thread Patch in this message |  | | From | Frederic Weisbecker <> | Subject | [PATCH 3/6] posix-cpu-timers: Force next expiration recalc after itimer reset | Date | Mon, 26 Jul 2021 14:55:10 +0200 |
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When an itimer deactivates a previously armed expiration, it simply doesn't do anything. As a result the process wide cputime counter keeps running and the tick dependency stays set until we reach the old ghost expiration value.
This can be reproduced with the following snippet:
void trigger_process_counter(void) { struct itimerval n = {};
n.it_value.tv_sec = 100; setitimer(ITIMER_VIRTUAL, &n, NULL); n.it_value.tv_sec = 0; setitimer(ITIMER_VIRTUAL, &n, NULL); }
Fix this with resetting the relevant base expiration. This is similar to disarming a timer.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com> --- kernel/time/posix-cpu-timers.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 61c78b62fe6a..5c71322b45c7 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1379,8 +1379,6 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid, } } - if (!*newval) - return; *newval += now; } -- 2.25.1
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